Compact Ejector System for a Boosted Internal Combustion Engine

ABSTRACT

Vapors in the fuel tank of a vehicle are collected in a carbon canister. An ejector or aspirator is used to purge the carbon canister in a pressure-charged engine in which a positive pressure exists in the intake. A compact ejector includes a substantially planar flange and a venturi tube coupled to the flange with a central axis of the venturi tube substantially parallel to the flange. By mounting the ejector on an intake component, having the venturi tube on the inside of the intake component, and having the venturi tube parallel to the flange yields a very compact package and protects the ejector from damage from other engine components.

FIELD OF INVENTION

The present disclosure relates to a vapor purge system for an internalcombustion engine, particularly related to an ejector for aiding purgeduring boosted operation.

BACKGROUND

Vehicles are equipped with an evaporative emission control system thattraps fuel vapors from the fuel tank of the vehicle and stores them in acanister in which charcoal particles or other suitable media aredisposed. The fuel vapors are absorbed onto the charcoal particles. Toavoid overloading the canister such that the charcoal particles have nofurther capacity to absorb fuel vapors, the canister is purgedregularly.

In a naturally-aspirated internal combustion engine, the pressure in theintake manifold is depressed. This vacuum is used to draw fresh airthrough the canister.

The vapor-laden air is then inducted into the engine and combusted. Apurge valve or port is provided that fluidly couples the canister withthe intake of the engine when purging is desired.

In boosted engines, i.e., turbocharged, supercharged, or boosted by anysuitable device, pressure in the engine's intake is often aboveatmospheric thereby reducing the available times for purging. To obtaina vacuum to drive purge flow, a tube with a throat (reduced diametersection) causes a higher flowrate which causes the vacuum. The componentin which the throat is included is called an ejector or an aspirator.

An example of a prior art configuration in FIG. 1. An engine 10 has anair intake system including a manifold 12 and a throttle body 14.Throttle body 14 has an air passage 16 and a throttle valve 18 tocontrol the quantity of air flowing into manifold 12. Throttle body 14has an inlet 20 fluidly connected to an outlet 22 of a turbochargerassembly 24.

Turbocharger assembly 24 includes a compressor 26 and a turbine 28.Compressor 26 and turbine 28 are both mounted upon a common shaft 30.Exhaust gases are directed through a duct 32 to turbine 28 anddischarged through an outlet tube 34.

Compressor 26 receives air from an inlet duct 36. Air is pressurized bycompressor 26 and discharged into outlet 22 and then into throttle body14 or charge air cooler into manifold 12 and then into engine 10.

Modern engines are equipped with vapor emission control systems whichinclude a fuel vapor storage canister 38. Vapor storage canister 38 hasa quantity of activated charcoal particles 40 or other suitableadsorbent material. Activated charcoal absorbs fuel vapor and storesthem. Charcoal particles 40 are secured between a lower screen 42 and anupper screen 44. Fuel vapors and air are routed to the interior ofcanister 38.

Charcoal 40 has a finite storage capacity of fuel vapor. Therefore, thecanister is purged periodically to remove fuel vapor from the charcoalby drawing air from the atmosphere into the canister and through theactivated charcoal bed. Atmospheric air flows through picks up moleculesof fuel vapor in an adsorption process. The fuel laden air is drawinginto combustion chambers of engine 10 and burned. An air inlet 46 isprovided to allow purge air to engine canister 38. Air from inlet 46passes downward through a duct 48 to a space 50 beneath the screen 42and above the bottom of canister 38.

Canister 38 has an outlet opening 52 to allow purge air and fuel vaporsto be discharged from canister 38. Normally, purge air and fuel vapor isdesorbed from the charcoal through a conduit 54 to either of conduits 56or 58; alternatively, the conduit can be coupled to the intake manifold.When engine 10 is idling, throttle valve 18 assumes a position 18′ andthe interior of throttle body 14 downstream of throttle valve 18 is at avacuum. During this period, purge air is drawn from conduit 56 throughan orifice 60. Excessive purge can interfere with engine performance. Afuel vapor management valve 62 controls air-fuel vapor purge based onengine operating conditions into intake manifold 12.

When engine 10 is operating at part throttle, i.e. with throttle valve18 between the idle position and wide open throttle (position shown aselement 18 in FIG. 1). The portion of throttle body 14 upstream ofthrottle valve 18 is exposed to manifold vacuum pressure. This vacuumincludes air flow through conduit 58, check valve 64, an orifice 66, andport 68 into throttle body 14. Purge flow is influenced by the relativeposition of throttle valve 18 to port 68 and by the size of the orifice.Orifice 66 limits the purge air flow into engine 10 as appropriate forgood operation.

When engine 10 is operating under boost conditions, compressor 26generates a greater pressure at outlet 22 of turbocharger 24 than atinlet 36. Under these conditions, compressor 26 generates a positivepressure in throttle body 14 and in manifold 12. Check valves 62, 64prevent air flow from throttle body 14. The positive pressure at outlet22 causes air to flow through a conduit 70 to an inlet end portion 72 ofan ejector 74. Ejector 74 includes a housing defining inlet end portion72, outlet end portion 66 and a reduced dimension passage 78 (throat)there between. Air passes from inlet 72 through throat 78 to an outlet76 and then through conduit 80 to inlet 36 of compressor 26. Flow of airthrough throat 78 reduces pressure as is well known by one skilled inthe art.

Ejector 74 also includes a purge air passage 82 which opens into passage78. Conduit 54 is connected to the purge air passage of ejector 74. Acheck valve 84 allows the flow of air and vapors from conduit 54 intopassage 82 and then into passage 78. Finally, purge air and vapor passthrough conduit 70 into throttle body 14 and then into engine 10. Duringnon-boost operation of engine 10, check valve 84 prevents air flow fromejector 74 back to canister 38.

The above-described emissions control operates effectively to routepurged vapors to engine 10 and treatment by a catalytic converter (notshown). However, under some conditions, it is undesirable to purgecanister 38. For example, when the catalytic converter is too cool toeffectively process exhaust gases, provision is made to prevent canisterpurging. A control valve 86 is provided downstream of outlet opening 52from canister 38. Valve 86 has an outlet port 88 formed by a valve seat90. A movable valving member such as a diaphragm 92 is normallypositioned by a spring 94 against seat 90 so that air cannot flowthrough valve 86. This is the condition of the valve when no purge isdesired as mentioned above.

When air flow through valve 86 is desired, a vacuum pressure isintroduced into valve 86 above the diaphragm 92 which unblocks port 88.Vacuum is directed to valve 86 through a conduit 96 which is connectedto a port of a solenoid controlled on-off valve 98. Another port ofvalve 108 is connected to a conduit 100. In turn, the conduit isconnected to a conduit 104. An electric solenoid valve 108 is connectedto a conduit 100. In turn, conduit 100 is connected to check valve 102which is connected to a conduit 104. When open, vacuum is communicatedto the space above diaphragm 92 thus allowing purging. When closed, novacuum is routed to the space above diaphragm 92 thus allowing purging.When closed, no vacuum is routed to the space above the diaphragm andport 88 is blocked thus preventing purging of canister 38. Solenoidvalve 108 is commanded to energize by an engine electronic control unit110 (ECU).

The componentry shown in FIG. 1 is provided merely as background to thepresent disclosure and is not intended to be limiting in any way. Thecomponents are known to be coupled in alternative ways to that shown inFIG. 1.

Ejector 74 of FIG. 1 suffers from multiple deficiencies. It is astand-alone part that must be separately packaged, protected fromdamage, and supported. It is known to mount an ejector on an engineintake component, such as shown in FIG. 4. Referring first to FIG. 2, anejector 120 is shown that has a flange 122 through which tubes 124 and126 extend. Ejector 120 is shown in cross section in FIG. 3. Disposed intube 124 is an insert 130 with a reduced cross section. Insert 130 has athroat 132 with a small cross section. The speed at which gases movethrough throat 132 is much greater than the speed of the flow at aninlet of tube 124. Downstream of insert 130 is a straight section 136.It would be preferable to have this be a diverging tube. Prior artmanufacturing methods led to tube 136 being straight. Tube 134 couplesto tube 124 at the location of throat 132 via a tee tube 134 to therebyinduce flow through 126. In the fabrication of ejector 120, the insidediameter of tube 134 is formed through an orifice proximate a plug 128.After fabrication, tee tube 134 is sealed via plug 128. Ejector 120 isshown mounted to an air box 150 in FIG. 4.

The ejector system shown in FIG. 4 presents some deficiencies. Referringto FIG. 4, the depth that the ejector extends into air box 150 is shownby numeral 140 and the width of ejector 120 within air box 150 is shownby numeral 142 in FIG. 3. This presents considerable encroachment on theinterior of air box 150. Air boxes have unique designs depending on theengine, the vehicle, and other package considerations such as otheraccessories. Although it would be desirable for a vehicle manufacturerto have three or four standard air boxes, in reality, there is littlecrossover among different vehicles. It is likely that many uniqueejectors would be required to mate to a variety of air boxes. Theconsiderable encroachment can also cause higher flow restriction for theair passing through the duct. The ejector of FIGS. 2-4 has threeelements: the main body of ejector 120, a cap 144, and insert 130.Insert 130 is sometimes molded separately to avoid a molding process inwhich a thin pin is used to form the opening. A tube 136 downstream ofinsert 130 is straight because a pin is pulled to form tube 136. This isnot the preferred shape, simply what is available based on themanufacturing process. Disadvantages in the prior art include: therequirement of molding a separate piece for the insert and a plug;obtaining an ejector with less than desired flow characteristics (due tohaving straight section downstream of the throat); and the resultingejector is bulkier than desired.

An ejector that is compact and easy to manufacture while maintainingtight tolerances, particularly in the throat area, is desired.

SUMMARY

To overcome at least one problem in the prior art, an ejector for acanister purge system of a boosted engine is disclosed that has aflange, a venturi tube coupled to the flange, and first and second tubesextending through the flange. The first tube fluidly couples to one endof the venturi tube. The second tube fluidly couples to a downstream endof a throat of the venturi tube. The ejector comprises first and secondpieces coupled together. The first piece comprises the first and secondtubes, the flange, and an upper half of the venturi tube. The secondpiece comprises a lower half of the venturi tube.

The flange is substantially planar and a centerline of the venturi tubeis substantially parallel to the flange.

The second tube is substantially perpendicular to the flange and acenterline of the first tube and a centerline of the second tube form anacute angle. Or in other embodiments, a centerline of the first tube anda centerline of the second tube are substantially parallel; and thecenterline of the first tube is substantially perpendicular to theflange.

The first piece and the second piece are coupled sonic welding,vibration welding, induction welding, laser welding, ultrasonic welding,hot plate, and infrared welding, or thermal welding. In otherembodiments, the first and second pieces are coupled by a plurality ofsnap fit connectors arranged around the periphery of the first andsecond pieces. A seal between the first and second pieces is provided byone of: an adhesive material provided on the interface surfaces of thefirst and second pieces and a groove in at least one of the interfacesurfaces with an O-ring disposed in the groove. In some embodiments, theseal is unnecessary.

The venturi tube comprises a converging section to which the first tubeis fluidly coupled, the throat, and a diverging section. In someembodiments, the throat diverges.

In some embodiments, a centerline of the diverging section anglesdownward slightly with respect to the flange. In some embodiments, thediverging section has a circular cross section at the throat and a crosssection of a flattened circle at the exit with the portion of the circlethat is flattened is proximate the flange.

Also disclosed is an ejector system with an ejector that includes aventuri tube having a converging section, a throat, and a divergingsection; a first tube fluidly coupled to the converging section; and asecond tube fluidly coupled to the throat. The venturi tube has firstand second pieces welded together.

An interface between the first and second pieces of the ejector issubstantially coincident with a diameter of the venturi tube.

The first piece of the ejector includes the first and second tubes and aflange through which the first and second tubes pass.

The ejector system further has an intake system component defining anopening and having a flat surface at the periphery of the opening. Aperiphery of the flange also has a flat surface. The flat surface of theflange is welded or otherwise attached or integrated to the flat surfaceof the opening associated with the intake system component.

The intake system component is an air cleaner box or an air duct.

Flash traps are provided adjacent to the surface of the openingassociated with the intake system component. Such flash traps largelyprevent flowing material from getting into places that would interferewith the performance of the ejector.

At least one flash trap is provided in the flange of the ejectorimmediately adjacent to the surface of the flange that is welded to theintake system component.

The first tube is also fluidly coupled to an air intake and the secondtube is also fluidly coupled to a volume associated with a fuel tank.

An ejector system for a boosted engine includes: an air duct and anejector coupled to the air duct. The ejector has: a first piece having afirst tube, a second tube, a flange with a flat surface around theperiphery, and a first portion of a venturi tube; and a second piecethat is coupled to the first piece and comprises a second portion of theventuri tube. The first and second pieces are affixed by welding, snapfitting, and mechanical fasteners.

The air duct defines an opening with a flat surface surrounding theopening. The flange of the ejector has a flat surface that interfaceswith the flat surface of the air duct. The flat surface of the ejectoris welded to the flat surface of the air duct with the venturi tube ofthe ejector located inside the air duct.

The venturi tube of the ejector includes a converging section, a throat,and a diverging section. A centerline of the converging section and acenterlines of the throat are substantially parallel to the flange. Acenterline of the diverging section dips downward from plane of theflange as considered in the direction of flow.

In one embodiment, an ejector for a canister purge system of a boostedengine, includes: a flange; a venturi tube coupled to the flange, theventuri tube comprising a converging section, a throat, and a divergingsection (alternatively called a diffuser); a first tube fluidly coupledto the venturi tube upstream of the converging section; a second tubefluidly coupled immediately downstream of the throat; and an intakesystem component defining an opening and having a surface at theperiphery of the opening. A periphery of the flange has a surface thatis affixed to the surface of the opening associated with the intakesystem component.

In some embodiments in which the first and second pieces of the ejectorare welded, one of the two pieces of the ejector has a skirt extendingfrom a periphery of the ejector. The skirt forms a butt weld and themating surfaces form a butt weld. The skirt serves as a pilot to locatethe two pieces before welding.

The ejector is formed by one of: injection molding, 3-D printing,casting, vacuum forming, blow molding, rotomolding, resin transfermolding, and machining from a blank.

In some embodiments, a centerline of the diverging section is offsetfrom a centerline of the converging section of the venturi tube. Theoffset can be in vertically upward or downward direction.

The ejector is affixed to the intake air component by one of: a weld,screws, mechanical fasteners, rivets, and an adhesive.

In some embodiments, the ejector is a single piece, such as with 3-Dprinting. In other embodiments, the majority of the ejector is made in asingle piece with a plug in one end. The plug could be threaded oraffixed in any suitable manner. Such embodiments are suitable fortraditional casting processes or machining from a blank, as non-limitingexamples.

In some ejectors one of the tube is canted with respect to the flange inin some embodiments both tubes are canted with respect to the flange,i.e., a centerline of the tube forms an acute angle with the flange.

To prevent recirculation at some operating conditions, it has been foundhelpful to provide a divot that extends into the flow path of thediverging section of the ejector. In some embodiments, the divot is likean extended tear drop and in other embodiments, it is squared off. Othershapes are also within the scope of the disclosure.

By placing the venturi tube within the air system component, the ejectorsystem is more protected from potential breakage by carelessness or in acrash than when the ejector is primarily external.

Having the venturi tube substantially parallel to the flange of theejector means the ejector extends into the air system component to whichit is affixed to a much lesser extent than if the venturi tube isperpendicular to the flange, such as in the prior art shown in FIGS. 2and 3.

Advantages of the disclosed embodiments include: simplifiedconstruction, improved quality, fewer parts, lower piece cost, lowertooling investment, fewer assembly steps, lower weight, and morereliable and repeatable manufacturing and assembly.

In applications where packaging is tight, the embodiment in which one ofthe tubes is canted with respected to the other tube shortens theejector length. If further shortening is desired, the flange isshortened in the vicinity of the exit of the diverging section. Bothshortening embodiments can be combined to provide a very compactinjector.

In the prior art method of making an ejector, as will be discussed inmore detail below, a pin is used to form the throat. In someapplications, the pin to form the throat of the venturi is so thin andlong that it is very likely to break causing manufacturing downtime. Theejector disclosed herein eliminates such need for a pin at all.

Another issue that occurs due to the pin is molding flash, i.e., excessmaterial that moves into a spot wherein it is not intended to be. Forthe converging and diverging sections of the venturi, the diameter isfairly large and a bit of flashing doesn't cause substantial blockage.It may disrupt the flow a bit and cause some flow losses. However,flashing in the throat area is particularly troublesome and will causevariation in performance, at least, and will likely fail. Furthermore,it could become a source of contamination. It is a quality problem and ascrap problem.

The ejector according to embodiments disclosed herein provide asubstantial performance advantage of about 25% greater flow over theboost range compared to prior art ejectors. The reason for the advantagein flow is due to the two-piece sectioning of the ejector through theventuri affording the ability to optimize the geometry in the venturi.The advantage also applies to one-piece ejectors in which the geometryis similarly controlled in a manner superior to prior art ejectors.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a canister purge system which includes anejector according to the prior art;

FIG. 2 is a prior art ejector;

FIG. 3 is the ejector of FIG. 2 in cross section;

FIG. 4 is the ejector of FIG. 2 shown installed in an air box;

FIG. 5 is an ejector according to an embodiment of the disclosure;

FIG. 6 is the ejector of FIG. 5 shown in cross section;

FIG. 7 is an ejector according to an embodiment of the disclosure shownin cross section;

FIG. 8 is a cross section of an exit section of a venturi tube accordingto an embodiment of the disclosure;

FIG. 9 is a graph of flowrate as a function of boost pressure comparinga prior art ejector and a presently disclosed ejector;

FIGS. 10 and 11 are cross sections of a portion of ejectors having snapfit connections;

FIG. 12 is a flowchart illustrating a prior art process by which anejector can be fabricated;

FIG. 13 is a flowchart illustrating a process, according to the presentdisclosure, by which an ejector can be fabricated;

FIGS. 14 and 15 are flowcharts showing alternative processes to thoseshown in FIG. 13;

FIG. 16 is a flowchart showing processes involved in installing theejector into an engine air component;

FIG. 17 is an illustration showing an air duct and an ejector prior toassembly;

FIG. 18 is a cross section of the air duct and the ejector afterassembly;

FIG. 19 is a cross-sectional view of a shortened ejector;

FIG. 20 is an illustration showing an air duct with the shortenedejector of FIG. 19 prior to assembly;

FIG. 21 is a one-piece embodiment of the ejector that provides tighttolerance for the diverging section, the converging section, and thethroat;

FIG. 22 is a two-piece embodiment of the ejector in which the centerlineof the converging section is offset from the centerline of the divergingsection;

FIG. 23 is a cross section of a two-piece ejector that is coupled via asnap fit and sealed by interference lobes;

FIG. 24 is an expanded, cross-sectional view of a portion of the twopieces of ejector, showing an energy director and a skirt;

FIG. 25 is an isometric view of an ejector having a divot proximate theexit of the diverging section;

FIGS. 26 and 27 are two views of the diverging section of the ejector ofFIG. 25; and

FIG. 28 is an isometric view of an ejector having a squared off divotproximate the exit of the diverging section.

DETAILED DESCRIPTION

As those of ordinary skill in the art will understand, various featuresof the embodiments illustrated and described with reference to any oneof the Figures may be combined with features illustrated in one or moreother Figures to produce alternative embodiments that are not explicitlyillustrated or described. The combinations of features illustratedprovide representative embodiments for typical applications. However,various combinations and modifications of the features consistent withthe teachings of the present disclosure may be desired for particularapplications or implementations. Those of ordinary skill in the art mayrecognize similar applications or implementations whether or notexplicitly described or illustrated.

One embodiment of an ejector 150 according to the disclosure is shown inFIGS. 5 and 6. Ejector 150 has a flange 152 with a surface 154. Surface154 allows coupling with the periphery of an opening in an intakecomponent. Flange 152 has a first tube 160 having a centerline 164 and asecond tube 162 having a centerline 166 extending there through. Firsttube 160 is coupled to an air inlet (not shown) to bring in fresh air.

Second tube 162 is coupled to a carbon canister (also not shown) topurge the carbon canister. A venturi tube 170 is at the bottom ofejector 150. A first end 172 of venturi tube 170 is closed and a secondend 174 is open. The fresh air through first tube 160 and the fuel vaporladen gases of second tube 162 that are mixed in venturi tube 170 exitsthrough second end 174. Ejector 150 is made up of two pieces that arewelded together at an interfaces of the two parts to form weld joint176. Weld joint 176 is slightly angled in ejector 150. In otherembodiments, weld joint is planar. The first piece includes the elementsabove weld joint 176, i.e., first tube 160, second tube 162, flange 152and an upper portion of venturi tube 170. The second piece includes alower portion of venturi tube 170.

Weld joint 176 is substantially parallel to flange 152 and is coincidentwith a diameter of an opening through venturi tube 170. Referring now toFIG. 6, which is a cross-sectional view of FIG. 5, an internal shape ofventuri tube is shown. An entrance section 180 receives fresh air fromtube 160. The purpose of entrance section 180 is to straighten the flowafter traveling through the 90-degree bend between tube 160 and entrancesection 180. A converging section 182 is downstream of entrance section180. Flow is accelerated in converging section 182. Flow from converging182 is introduced into a throat 184. Throat 184 includes the smallestcross-sectional portion of venturi tube 170. The embodiment of throat184 shown in FIG. 6 slightly diverges. The downstream end of second tube162 couples to venturi tube 170 immediately downstream throat 184. As iswell known by one skilled in the art, the acceleration of flow in thethroat area leads to a drop in pressure, which draws the flow throughtube 162. Downstream of throat 184 is diverging section 186. In theembodiment in FIG. 6, a centerline of diverging section 184 dipsdownward as considered from left to right. This improves flowcharacteristics. In other embodiments, the centerline of the venturitube is straight. In some embodiments, such as shown in FIG. 6, tube 162expands near a downstream end, such as the portion 165 of tube 162shows. In some embodiments, the weld between the two pieces of ejector150 in FIG. 6 is a combination of a butt weld at the interface betweenthe two surfaces and a shear weld. The shear weld comes about byproviding a skirt 168 on the lower piece of ejector 150 that extendstoward the upper piece. In an alternative embodiment, the skirt can beprovided on the upper piece of ejector 150.

Referring to FIG. 7, an alternative embodiment of an ejector 200 isshown that includes a flange 202 and first and second tubes 210 and 212,respectively, which extend through flange 202. First tube 210 is cantedwith respect to second tube 212. A centerline 220 of first tube 210forms an acute angle 230 with respect to flange 202. An advantage ofsuch a configuration is that tube 210 doubles as an entrance section ofthe venturi tube. A converging section 232 couples directly with firsttube 210. A throat 234 is downstream of converging section 232. Adiverging section 226 is downstream of throat 234. Ejector 200 is madeup of two separately formed pieces that are affixed at a weld joint 226.Alternatively, these can be snap fit, twist locked, mechanicallyfastened, or coupled with an adhesive.

One of the advantage of ejector 200 of FIG. 7 is that the length ofejector 200 is shown as 240 compared to length 190 of ejector 150 ofFIG. 6 is shorter. Such a configuration requires a smaller opening in anair intake component to accommodate it. In an application where theintake duct has many curves and bends, there may be only a short sectionthat is straight enough to accommodate the ejector. Thus, a shortejector is particularly useful in certain applications.

As will be discussed below, ejector 200 is coupled to an air intakecomponent. In some embodiments, a surface 240 on the underside of flange202 interfaces or mates with a surface on the intake air component. Asdiscussed, some of the material is displaced into a place where it isnot wanted during the molding process, molding flash. When ejector 200is welded to the air intake component, welding flash develops. Topresent welding flash from going into places that would interfere withthe function of the ejector, flash traps 242 and 244 are provided oneither side of ejector 200.

Analysis of the design has indicated that it is preferable for exitcross section of the ejector (150, 200, as examples) to be a flattenedcircle. An exit 190 of an ejector is shown in FIG. 8. The upper portion192 of exit 190 is flattened. Exit 190 is made up of two pieces that arewelded together at interfaces 194.

Flowrate 850 of a prior art ejector and flowrate 860 of the ejector ofFIGS. 7 and 8 have been compared and are shown in FIG. 9. The ejector,according to the present disclosure, has significantly improved flowrateat all boost pressures. The improved flowrate is due to the venturi tubehaving a distinct converging and diverging sections rather than straighttubes found in the prior art.

In an alternative embodiment in FIG. 10, an alternative method ofaffixing the upper piece 502 and lower piece 504 of a cross section of aportion of an ejector 500 is shown. Lower piece 504 is provided with agroove 506 in a face of lower piece 504 that interfaces with lower piece502. An O-ring 508 is placed into groove 506. Upper piece 502 isprovided with a recess 510 along an outer surface. Recess 510 does notextend all the way to the interface with lower piece 502. A lip 514extends outwardly. Lower piece 512 is molded with a flexible finger 510that engages with lip 514.

In another embodiment in FIG. 11, a cross section of a portion of anejector 520 has an upper piece 522 and a lower piece 524. Upper piece520 has a wedge 530 that extends outwardly from the surface. Lower piece524 has a flexible finger 532 that engages with wedge 530. In theembodiment in FIG. 11, an adhesive 526 has been applied to the interfacesurface of upper part 522 and/or the interface surface of lower part524. In the discussion of FIGS. 10 and 11, the flexible finger is on thelower part. However, this is simply a non-limiting example. Variationsof these examples are also within the scope of the disclosure

The improved design of the ejector disclosed herein is at leastpartially due to a new method of manufacturing such ejectors. A priorart process is shown in FIG. 12. In blocks 300 and 302, the resin toprovide to the injector molder is of the appropriate specification andthat is properly dried, respectively. In block 304, the resin isinjected into the three molds to produce: an ejector body, a plug, andan orifice piece that includes at least the throat of the venturi. Theorifice part is molded separately because the orifice size at the throatis small. It is possible to integrate the orifice piece into the ejectorbody. However, a thin pin is required to form the throat. A rule ofthumb is that the length of the pin should be no more than 3.5 times thediameter of the pin. Such a pin for an integrated throat would exceedthis safe number by at least an order of magnitude. Such a thin pin thatmuch extend into the ejector body at such a distance is likely to leadto failures of the pin. This causes breakage, downtime, increases scrap,and generally increases the cost of the manufacturing process. The morerobust method to manufacture, according to the prior art, is to make theorifice piece separately. In block 306, the orifice part is insertedinto the ejector body. Each of the ejector bodies is inspected in block308. If improperly installed, the part is rejected in block 310. Ifproper installation, the plug is affixed to the ejector body in block312. In the prior art ejector such as shown in FIGS. 2 and 3, almost theentire ejector is formed in one piece. To form tube 134 of FIG. 3, anopening at one end is provided that is closed off by plug 144.

Quality assurance measures begin in block 350 in which all of leak, flowand vacuum draw are measured and it is determined whether they are inacceptable ranges. If so, the ejector is ready for assembly into anengine intake component, in block 352. If out of specification in block350, it is determined whether the flaw was caused by the molding processor molding flash (excess material on the part) in block 360. If that isdetermined to be the issue, in block 362, the molding process isadjusted or machine maintenance is performed and it is verified that thecorrection is effective before resuming. If a negative result from block360, in block 370, it is determined whether the flaw was caused by thewelding process. If so, the weld tooling or process is adjusted in block372. Also, in block 372, it is determined whether the correction iseffective. If a negative result in block 370, in block 380, it isdetermined whether the flaw is caused by excess moisture and/or whetherthe resin material is out of specification. If the dryness is causingthe flaw, the material drying process is adjusted and verified. If thematerial is out of specification, the proper material is obtained andloaded into the molding machine, in block 382. In any case with an outof specification part, the part is scrapped in block 392. If a negativeresult in block 390, additional review of the processes is continueduntil cause of the flaw is determined and rectified.

A flow chart showing processes undertaken to produce the disclosedejector is shown in FIG. 13. Blocks 300, 302, 350, 352, etc. are mostlythe same for the disclosed process and the prior art process. Thus, theyare not separately described here. Starting in block 320, the upper andlower pieces of the ejector are injection molded. In block 322, the twopieces are affixed. In one embodiment, the pieces are affixed bywelding: sonic, ultrasonic, thermal, or any suitable type of welding. Analternative embodiment is shown in FIG. 14 in which an O-ring is placedin a groove in an interface of the first or second pieces in block 324.One of the first and second pieces has a flexible finger that engageswith a feature on the other piece in block 326. When the pieces aresnapped together, the O-ring is pressed into the groove and seals thefirst piece with the second piece. In another alternative in FIG. 15,the interfaces between the first and second piece is flat. At least oneof the interfaces has adhesive applied, block 328, so that when thefirst and second pieces are snapped together in block 330, the adhesiveseals the interface between the first and second pieces.

In FIG. 16, an ejector is manufactured in block 400, such as by theprocess in FIGS. 13-16. In block 402, the air intake component ismanufactured with an opening to accommodate the ejector. In someembodiments, the flange of the ejector is as short as possible so thatthe opening in the intake air component is as small as possible. This isparticularly useful when the desired location is in an engine duct withlots of turns, i.e., a limited straight run to accommodate the ejector.In such cases with short flanges, the exit portion of the ejector istilted downward to access the opening in block 410. In some otherembodiments, the ejector can be put into the orifice directly withouttilting. In block 412, the interface of the flange of the ejector isaligned with the interface of the air intake component, i.e., a raisedportion around the opening in the air intake component that is providedfor this purpose. The ejector is welded onto the intake air component,in block 414.

In FIG. 17, an ejector 600 is shown above an air duct 610 prior toassembly. Ejector 600 has a flange 602, first and second tubes 604 and606, and a venturi tube 608. Air duct 610 has a protuberance 618 thataccommodates forming a flat surface 616 onto which a flange 602 mounts.Surface 616 surrounds an opening 614 into which venturi tube 608 beplaced. Opening 614 is large enough to allow venturi tube 608 to go intoopening 614 straight on, as shown by arrows 630. Ejector 600 is affixedto air duct 610 by friction welding or any other suitable process. Across section of an ejector-air duct assembly is shown in FIG. 18. Theunderside of flange 602 is affixed to the periphery of the opening,surface 616 of FIG. 17.

The duct shown in FIGS. 17 and 18 has a straight section that is longenough to accommodate an opening 614 (shown in FIG. 17) for ejector 610.However, in some applications, air ducts have limited ability toaccommodate ejector 610, or even the shorter ejector shown in FIG. 7. Ashorter version of ejector 150 of FIG. 6 is shown in FIG. 19. Ejector188 is nearly identical to ejector 150, of FIG. 6, except that flange192 couples to diverging section 174 at location 196, which is closer totube 162 than in FIG. 6. The length of ejector 188 is shown having alength 198 in FIG. 19, which is shorter than ejector 150 of FIG. 6 thathas a length 190.

In FIG. 20, a shortened ejector 640 is shown that has a shortened flange642 (similar to the shortened flange in FIG. 19) with tubes 604 and 606extending from flange 642. Air duct 650 has a protuberance 658 that hasan opening 654 (also shortened) that has a surrounding surface 656 towhich flange 642 is affixed. Because venturi tube 608 sticks out beyondflange 642 compared to venturi tube 608 in relation to flange 602 ofFIG. 17, venturi tube 608 cannot be installed into opening 654 directlybut must be tipped, as shown in FIG. 20. After venturi tube 608 entersopening 654, ejector 640 can be straightened out so that flange 642meets with surface 656. This tilting and then straightening isillustrated by arrow 660.

It is known to manufacture the ejectors by injection molding. In theprior art, such manufacturing technique leads to the difficulty inmaking diverging and converging sections in the ejector because suchsections are formed by cylindrical pins. According to embodimentsdisclosed above, the two-piece version that is split along venturi tubeallows a complicated shape can be formed with a converging section, adiverging section, and a throat, that in some embodiments, slightlydiverges. In the prior art, throats are typical straight. However, insome applications, it has been found that the diverging throat yieldsimproved flow efficiency approaching supersonic flow. In someembodiments, the diverging section has a non-uniform shape and in someembodiments, tilts downwardly; such features are easily accomplishedwith the two-piece ejector disclosed herein. Although it might be lessexpensive to injection mold the ejector out of two pieces, there arealternative manufacturing techniques that allow the desired shape in onepiece. A 3-D printing process is one alternative. The resulting could belike any of FIGS. 5-7, except that the ejector would be of one piece.The difference between a 3-D printed ejector according to an embodimentof the present disclosure compared to the prior art in FIGS. 2-4 is thatthe ejector in FIGS. 2-4 have straight tube, whereas a 3-D printedejector can have a converging section, a throat of controlled diameter,and a diverging section. In yet another embodiment shown in FIG. 21, anejector, according an embodiment of the disclosure, is formed in onepiece via a traditional casting method. To remove the core pieces, i.e.,that provide the openings within the venturi tube, a plug is providedproximate the upstream end of the venturi tube. Finally, although verycostly, the ejector can be machined from a blank.

In FIG. 22, an ejector 710 has a throat 715 with a converging section tothe left (upstream) and a diverging section to the right (downstream). Acenterline 712 of the converging section is offset from a centerline 714of the diverging section. A left tube 716 of ejector 710 is canted. Aright tube 718 is also canted in ejector 710. It has been found throughmodeling that such an offset provides greater flow, particularly whenboth tube 716 and 718 are canted as shown in FIG. 22.

As described above, some embodiments show a snap fit to affix the twopieces of the ejector. In such embodiments, an O-ring, adhesive, orother sealant can be used. Alternatively, a bump near the periphery ofone of the pieces causes an interference with the other piece of theejector, as shown in FIG. 23. An ejector 720 has a first piece 722 and asecond piece 724. Second piece 724 has flexible fingers 730 and 732 tosnap fit around bosses 740 and 742, respectively. FIG. 3 is only forillustration purposes to show two ways that ejector pieces 722 and 724can be sealed. On the left hand side of FIG. 23, a ridge 750 extendsoutwardly from boss 740. Ridge 750 causes an interference with an innerwall of flexible finger 730. On the right hand side of FIG. 23 shows analternative sealing where a ridge 752 extends from boss 742 towardsecond piece 724. Ridge 752 causes and interference with an uppersurface of second piece 724 proximate boss 742.

In FIG. 24, a detail of a lower portion 900 of the ejector is shown. Asurface 902 has an energy director 904 that is useful in the weldingprocess. Energy director 904 is typically sits proud of the surface byabout 0.6 mm. Surface 902 forms a butt weld with respect to a matingsurface (not shown). A skirt 908 has two functions: serves as a pilot tolocate the mating surface during assembly. Furthermore, the surface 908forms a shear weld with a portion of the mating part.

An isometric view of an ejector has a diverging section 1000 in which adivot 1002 is formed. FIG. 26 is a top view of diverging section 1000with divot 1002 and FIG. 27 is a side view. FIG. 28 shows an isometricview of an ejector 1100 in which a diverging section 1002 is providedwith a squared-off divot 1106 that has a short wall 1104. Divots 1002and 1106 are provided to prevent recirculation, which would diminishflow through the ejector, that occurs at some operating conditions.

While the best mode has been described in detail with respect toparticular embodiments, those familiar with the art will recognizevarious alternative designs and embodiments within the scope of thefollowing claims. While various embodiments may have been described asproviding advantages or being preferred over other embodiments withrespect to one or more desired characteristics, as one skilled in theart is aware, one or more characteristics may be compromised to achievedesired system attributes, which depend on the specific application andimplementation. These attributes include, but are not limited to: cost,efficiency, strength, durability, life cycle cost, marketability,appearance, packaging, size, serviceability, weight, manufacturability,ease of assembly, etc. The embodiments described herein that arecharacterized as less desirable than other embodiments or prior artimplementations with respect to one or more characteristics are notoutside the scope of the disclosure and may be desirable for particularapplications.

1. A compact ejector for a canister purge system of a boosted engine,comprising: a flange; a venturi tube coupled to the flange; and firstand second tubes extending through the flange wherein: the first tubefluidly couples to one end of the venturi tube; the second tube fluidlycouples to a downstream end of a throat of the venturi tube; the ejectorcomprises first and second pieces coupled together; the venturi tubecomprises first and second pieces coupled together; the first piececomprises the first and second tubes, the flange, and an upper portionof the venturi tube; and the second piece comprises a lower portion ofthe venturi tube.
 2. The ejector of claim 1 wherein the flange issubstantially planar and a centerline of the venturi tube issubstantially parallel to the flange.
 3. The ejector of claim 1 wherein:the second tube is substantially perpendicular to the flange; and acenterline of the first tube and a centerline of the second tube form anacute angle.
 4. The ejector of claim 1 wherein: a centerline of thefirst tube and a centerline of the second tube are substantiallyparallel; and the centerline of the first tube is substantiallyperpendicular to the flange.
 5. The ejector of claim 1 wherein the firstpiece and the second piece are coupled by one of sonic welding,ultrasonic welding, thermal welding, vibration welding, inductionwelding, laser welding, a hot plate, and infrared welding.
 6. Theejector of claim 1 wherein: the first and second pieces are coupled by aplurality of snap fit connectors arranged around the periphery of thefirst and second pieces.
 7. The ejector of claim 1 wherein: the venturitube comprises a converging section to which the first tube is fluidlycoupled, the throat, and a diverging section.
 8. The ejector of claim 74wherein at least one of the following characteristics of the divergingsection exists: a centerline of the diverging section angles downwardslightly with respect to the flange; and the diverging section has acircular cross section proximate the throat and across section of aflattened circle proximate an exit of the diverging section.
 9. Anejector system for a boosted engine, comprising: an air systemcomponent; an ejector coupled to the air system component, the ejectorcomprising: a first piece having a first tube, a second tube, a flangewith a surface around the periphery, and a first portion of a venturitube; and a second piece that is coupled to the first piece andcomprises a second portion of the venturi tube.
 10. The ejector systemof claim 9 wherein the first and second pieces are affixed by one ofwelding, snap fitting, and mechanical fasteners.
 11. The ejector systemof claim 9 wherein: the air system component defines an opening with asurface surrounding the opening; the flange of the ejector has a surfacethat interfaces with the surface of the air system component; and thesurface of the ejector is welded to the surface of the air systemcomponent with the venturi tube of the ejector located inside the airduct.
 12. The ejector system of claim 9 wherein: the venturi tube of theejector comprises a converging section, a throat, and a divergingsection; a centerline of the converging section and a centerline of thethroat are substantially parallel to the flange; and a centerline of thediverging section dips downward from plane of the flange as consideredin the direction of flow.
 13. The ejector system of claim 9 wherein theair system component is one of an air filter box and an intake air duct.14. The ejector system of claim 9 wherein when the first piece iscoupled to the second piece a seal between the first and second piecesis provided by one of: an adhesive material provided on the interfacesurfaces of the first and second pieces; and a groove in at least one ofthe interface surfaces with an O-ring disposed in the groove.
 15. Anejector system for a canister purge system of a boosted engine,comprising: a flange; a venturi tube coupled to the flange, the venturitube comprising a converging section, a throat, and a diverging section;a first tube fluidly coupled to the venturi tube upstream of theconverging section; a second tube fluidly coupled to the venturi tubeimmediately downstream of the throat; and an intake system componentdefining an opening and having a surface at the periphery of the openingwherein: a periphery of the flange has a surface; and the surface of theflange is affixed to the surface of the opening associated with theintake system component.
 16. The ejector of claim 15 wherein: theejector is comprised of two pieces that are coupled by one of a weldconnection and a snap fit connection; the first piece comprises thefirst tube, the second tube, the flange, and a first portion of theventuri tube; and the second piece comprises a second portion of theventuri tube.
 17. The ejector of claim 16 wherein one of the two piecesof the ejector has a skirt extending from a periphery of the ejector tothereby provide a butt and shear weld and a pilot for assembly.
 18. Theejector of claim 15 wherein the ejector is made by one of: injectionmolding, 3-D printing, casting, vacuum forming, blow molding,rotomolding, resin transfer molding, and machining from a blank.
 19. Theejector of claim 15 wherein a centerline of the diverging section isoffset from a centerline of the converging section of the venturi tube.20. The ejector of claim 15 wherein: the intake air component is one ofan intake air duct and an air filter box; the ejector is affixed to theintake air component by at least one of: a weld, screws, mechanicalfastener, rivets, and an adhesive.
 21. The ejector of claim 15 whereinat least one of: a centerline of the first tube forms an acute anglewith the plane of the flange; and a centerline of the second tube formsan acute angle with the plane of the flange.
 22. The ejector of claim 15wherein near the outlet end of the diverging section, a divot extendsinto the flow path of the diverging section.